tweak OpenAI Harmony autoguess developer prefix and assistant end token (LostRuins#1673)

* tweak OpenAI Harmony autoguess developer prefix

* use <|end|> for adapter end

Author: kallewoof

kcpp_adapters/AutoGuess.json

@@ -190,12 +190,12 @@
     "search": ["<|start|>user<|message|>", "<|channel|>", "<|end|>"],
     "name": "OpenAI Harmony",
     "adapter": {
-        "system_start": "<|start|>developer<|message|>",
+        "system_start": "<|start|>developer<|message|># Instructions\n\n",
         "system_end": "<|end|>",
         "user_start": "<|start|>user<|message|>",
         "user_end": "<|end|>",
         "assistant_start": "<|start|>assistant<|channel|>final<|message|>",
-        "assistant_end": "<|return|>"
+        "assistant_end": "<|end|>"
     }
 }, {
     "search": ["rwkv_", "'User: '"],